Let a b c d be a circle in which it is required to draw a pentagon. Draw a diameter a d, and perpendicular to it another diameter.

Fig. 32.

Then divide o b into two equal parts in the point E, and join C E; and with e as a centre, and the radius C E, draw the arc C F, cutting a o in f; and, with c as a centre, and the same radius, describe the arc f G ; the arcs c f, g f intersect each other in the point f, and the arc G F intersects the circumference of the circle in the point G. Join the points c and G, and that line will be a side of the pentagon to be drawn. Mark off within the circumference the same space, and join the points a h, h i, i k, k c, and the figure that is formed is a pentagon.